This morning, the D.C. Circuit (finally) denied the petition for rehearing en banc in Al-Bihani v. Obama, its first post-Boumediene decision on the merits in a Guantanamo habeas case, and one that engendered a fair amount of criticism for its rather desultory treatment of whether international humanitarian law had any bearing on the government's detention authority under the 2001 Authorization for Use of Military Force (the panel said no, even though the government hadn't taken such an extreme view). [I've written before about some of the issues with the decision, and co-authored one of the amicus briefs in support of rehearing.]

There are 113 pages of opinions respecting the denial of rehearing en banc (a number that's even more significant when you realize that no one dissented from the denial), but the most important sentence comes on page 3, in a joint statement by Chief Judge Sentelle and Judges Ginsburg, Henderson, Rogers, Tatel, Garland, and Griffith (i.e., every active D.C. Circuit judge who was not on the original three-judge panel):

We decline to en banc this case to determine the role of international law-of-war principles in interpreting the AUMF because, as the various opinions issued in the case indicate, the panel’s discussion of that question is not necessary to the disposition of the merits.

In other words, without going en banc, the Court of Appeals held that the most troubling holding of the panel opinion wasn't a holding.

I'll save for after I've had a chance to read them more closely any analysis of the 15-page concurrence penned by Judge Brown (who wrote the panel opinion and a separate concurrence the first time around); the 87-page concurrence by Judge Kavanaugh; or the eight-page "statement" by Senior Judge Williams, all of which strike me at first blush as the original panel relitigating the original opinion. For present purposes, the significance of today's decision isn't the denial of rehearing en banc so much as it is the "dicta-ization" of the reasoning that had prompted many (myself included) to urge the D.C. Circuit to reconsider the panel decision in the first place. Whatever the merits of the decision in Al-Bihani's case, specifically, its significance in other cases has been unquestionably lessened (along with any chance that the Supreme Court would feel the need to step in).

The quoted passage does not say that the holding wasn't a holding or turn it into dicta. If there was any doubt, the extensive commentary by Brown and Kavanaugh shows that a majority of the panel do not interpret that part of the decision as dicta.

However, as Brown points out they reached their decision in Al-Bihani by apply redundant parallel legal arguments. One of those arguments is in dispute. In this statement the other judges decline to rehear en banc a case where there is no controversy, because the outcome has already been determined by arguments that are not subject to serious challenge.

Determining that a case should not be reheard because there is no controversy does not modify the previous holding or block its use as precedent. It may, however, reinforce a willingness of some other panel to disagree with the precedent in a case where the issue really matters, and that might lead to a meaningful en banc.